Let's get connected!

It’s been a good month(!!!) since I did a update on the devlog. So I figured I’d give you guys a new update on how things are going. The updates are going in a bit weird way this time, because I made an oopsie with my internet bill(I accidently forgot to pay a month, and they put a nice “Please pay us and you get internet access again kthx” banner whenever I browse to any website.

That’s the annoyance with all the moving around, you miss a bill and then they shut you off. However, they put a filter on my line at Friday afternoon 18:30, 30 minutes after closing their billing department. If they did it an hour earlier, I’d fix them up the bill immediately and there wouldn’t have been a problem.

But, this is good news for Dune. As I can’t waste my time on the internet, I decided to start coding up the network components for Dune.

Design

As opposed to earlier posts, I decided to actually go with a Client / Server setup instead of a star setup. The P2P star is difficult to set up and I couldn’t figure out a way to be 100% be sure all clients would have the correct amount of data to make sure they don’t go out of synch.

Downside in my current approach is that the host will have to have at least n times as much bandwidth as regular players, where n is the amount of players – 1. But, in a time of broadband, I doubt that’ll be a problem.

I still intend to go with the turn-based approach: Each set of commands is send 1 (or 2) turns ahead of the current one. Turns are executed at a determined interval(for instance, 200ms) on authority of the server. So, when turn 1 is running, and the server knows all the clients have received the commands required to execute turn 2, it’ll send a StartTurn 2. However, this will mean, that if 1 client has a roundtrip time above the turn-length, the game will start to lag at some point. In order to prevent this, I intend to add some form for heuristic to automatically adapt the turn-time based on client pings. However, this won’t do magic, because if pings are above 300 ~ 400ms, turns will take too long and players will notice lag between commanding a unit and actually executing it.

Implementation

At the moment, I’m implementing the basic server / client code. The server runs as a Task in the game, as it needs to be updated at least once per frame. Next to it the client runs its normal simulation at the moment.

I’m still doubting if I give the server its own simulation: That would mean the hosting player would run the game twice: Its own copy, and a server copy. On slow machines, this would mean it would lag(Or to be more precise, run at low FPS).

However, I could hand the Server task a reference to the client simulation and use that as a base. It could generate checksums of that and request checksums from other clients to compare and kick out-of-synch players. But, that’s too far ahead.

I intend to write the code that hosts a basic lobby and let’s other clients connect. No graphical goodness tho, just basic command line stuff like:
dune2.exe –host 2 –name or dune2.exe –join -name

Once a client can connect to the server I can add the code to start a game and just show the same scenario on both game instances. I think that’s a challenge on its own already.